1. Field of the Invention
The present invention relates to a novel bacteriophage, more particularly, a bacteriophage that has a specific bactericidal activity against Fowl Typhoid causing Salmonella Gallinarum (SG) and Pullorum disease-causing Salmonella Pullorum (SP). Further, the present invention relates to a composition for the prevention or treatment of infectious diseases caused by Salmonella Gallinarum or Salmonella Pullorum, comprising the bacteriophage as an active ingredient. Furthermore, the present invention relates to feed and drinking water for poultry, sanitizers and cleaners, comprising the bacteriophage as an active ingredient.
2. Background Art
Salmonella is a genus of the family Enterobacteriaceae, characterized as Gram-negative, facultatively anaerobic, non spore-forming, rod-shaped bacteria, and most strains are motile by flagella. Salmonella has an average genome GC content of 50-52%, which is similar to those of Escherichia coli and Shigella. The genus Salmonella is a pathogenic microorganism that causes infections in livestock as well as in humans. Salmonella enterica, a species of Salmonella bacterium, has a variety of serovars including Salmonella Gallinarum, Salmonella Pullorum, Salmonella Typhimurium, Salmonella Enteritis, Salmonella Typhi, Salmonella Choleraesuis and Salmonella derby (Bopp C A, Brenner F W, Wells J G, Strokebine N A. Escherichia, Shigella, Salmonella. In Murry P R, Baron E J, et al eds Manual of clinical Microbiology. 7th ed. Washington D.C. American Society for Microbiology 1999; 467-74; Ryan K J. Ray C G (editors) (2004)). Of them, Salmonella Typhimurium and Salmonella Enteritis are pathogenic for human and animals, Salmonella Typhi is a human-adapted pathogen, Salmonella Choleraesuis and Salmonella derby are swine-adapted pathogens, and Salmonella Gallinarum and Pullorum are fowl-adapted pathogens. Each serovar causes illness in that species, which results in tremendous damage to farmers and/or consumers.
A disease of domestic birds caused by Salmonella bacterium is Fowl Typhoid (FT), which is caused by a pathogen, Salmonella Gallinarum (hereinbelow, designated as SG). Fowl Typhoid (FT) is a septicemic disease of domestic birds such as chicken and turkey, and the course may be acute or chronic with high mortality. Recently, it has been reported that Fowl Typhoid frequently occurs in Europe, South America, Africa, and South-East Asia, and damages are increasing. Outbreaks of FT in Korea have been reported since 1992 and economic losses coupled by FT in brown, egg-laying chickens are very serious (Kwon Yong-Kook. 2001 annual report on avian diseases. information publication by National Veterinary Research & Quarantine Service. March, 2001; Kim Ae-Ran et al., The prevalence of pullorum disease-fowl typhoid in grandparent stock and parent stock in Korea, 2003, Korean J Vet Res (2006) 46(4): 347353). Pullorum Disease is also caused by one of the Salmonella bacteria, Salmonella Pullorum (hereinbelow, designated as SP). Pullorum disease occurs in any age or season, but young chicken is very susceptible to the disease. During the past one century, it has been a serious disease to young chickens at 1-2 weeks of age or younger by egg-transmitted infections in the world and Korea. Since the 80's, the occurrence has greatly decreased. However, it has been growing in the middle of the 90's.
In Korea, the outbreaks of Fowl Typhoid and Pullorum disease have been increasing since the 90's, inflicting economic damages to farmers. For this reason, a live attenuated SG vaccine has been used in broilers for the prevention of Fowl Typhoid from 2004 (Kim Ae-Ran et al., The prevalence of pullorum disease-fowl typhoid in grandparent stock and parent stock in Korea, 2003, Korean J Vet Res (2006) 46(4): 347˜353), while its efficacy is doubtful, and the live vaccine is not allowed to be used for layers because of the risk of egg-transmitted infections. Unfortunately, there are still no commercially available preventive strategies against Pullorum disease, unlike Fowl Typhoid. Thus, there is an urgent need for new ways to prevent Fowl Typhoid and Pullorum disease.
A Bacteriophage is a specialized type of virus that only infects and destroys bacteria, and can self-replicate only inside a host bacteria. A Bacteriophage consists of genetic material—the nucleic acid—single or double stranded DNA or RNA surrounded by a protein shell. There are three basic structural forms of bacteriophage: an icosahedral (twenty-sided) head with a tail, an icosahedral head without a tail, and a filamentous form. Bacteriophages are classified based on their morphological structure and genetic material. Based on their tail structure, bacteriophages having icosahedral head and double-stranded, linear DNA as their genetic material are divided into three families: Myoviridae, Siphoviridae, and Podoviridae, which are characterized by contractile, long noncontractile, and short noncontractile tails, respectively. Bacteriophages having icosahedral head without a tail and RNA or DNA as their genetic material are divided based on their head shape and components, and the presence of shell. Filamentous bacteriophages having DNA as their genetic material are divided based on their size, shape, shell, and filament components (H. W. Ackermann, Frequency of morphological phage descriptions in the year 2000; Arch Virol (2001) 146:843-857; Elizabeth Kutter et al. Bacteriophages biology and application; CRC press). During infection, a bacteriophage attaches to a bacterium and inserts its genetic material into the cell. After this a bacteriophage follows one of two life cycles, lytic or lysogenic. Lytic bacteriophages take over the machinery of the cell to make phage components. They then destroy or lyse the cell, releasing new phage particles. Lysogenic bacteriophages incorporate their nucleic acid into the chromosome of the host cell and replicate with it as a unit without destroying the cell. Under certain conditions, lysogenic phages can be induced to follow a lytic cycle (Elizabeth Kutter et al. Bacteriophages biology and application, CRC press).
After the discovery of bacteriophages, a great deal of faith was initially placed in their use for infectious-disease therapy. However, when broad spectrum antibiotics came into common use, bacteriophages were seen as unnecessary because of having a specific target spectrum. Nevertheless, the misuse and overuse of antibiotics resulted in rising concerns about antibiotic resistance and harmful effects of residual antibiotics in foods (Cislo, M et al. Bacteriophage treatment of suppurative skin infections. Arch Immunol. Ther. Exp. 1987.2:175-183; Kim sung-hun et al., Bacteriophage; New Alternative Antibiotics. biological research information center. BRIC). In particular, antimicrobial growth promoter (AGP), added to animal feed to enhance growth, is known to induce antibiotic resistance, and therefore, the ban of using antimicrobial growth promoter (AGP) has been recently introduced. In the European Union, the use of all antimicrobial growth promoters (AGPs) was banned from 2006. Korea banned the use of some AGPs, and is considering restrictions on the use of all AGPs.
These growing concerns about the use of antibiotics have led to a resurgence of interest in bacteriophage as an alternative to antibiotics. 7 bacteriophages for control of E. coli O157:H are disclosed in U.S. Pat. No. 6,485,902 (applied for in 2002—Use of bacteriophages for control of Escherichia coli O157). 2 bacteriophages for control of various microorganisms are disclosed in U.S. Pat. No. 6,942,858 (applied for by Nymox in 2005—Compositions containing bacteriophages and method of using bacteriophages to treat infections). Many companies have been actively trying to develop various products using bacteriophages. EBI food system (Europe) developed a food additive for preventing food poisoning caused by Listeria monocytogenes, named Listex-P100, which is the first bacteriophage product approved by the US FDA. A phage-based product, LMP-102 was also developed as a food additive against Listeria monocytogenes, approved as GRAS (Generally regarded as safe). In 2007, a phage-based wash produced by OmniLytics was developed to prevent E. coli 0157 contamination of beef during slaughter, approved by USDA's Food Safety and Inspection Service (FSIS). In Europe, Clostridium sporogenes phage NCIMB 30008 and Clostridium tyrobutiricum phage NCIMB 30008 were registered as a feed preservative against Clostridium contamination of feed in 2003 and 2005, respectively. Such studies show that research into bacteriophages for use as antibiotics against zoonotic pathogens in livestock products is presently ongoing.